The present invention relates generally to methods and devices for evaluating agriculture products, and more particularly, to assessing and monitoring the quality of agricultural products, such as food products, using electronic noses.
In general, electronic noses comprise an array of chemical sensing elements and a pattern recognition system. Electronic noses are designed to analyze complex vapors as they exist and produce a unique signature output. The sensor array is designed to respond to many different individual and complex compounds, analytes and vapors.
One recognized area of commercial interest for electronic noses is the food industry. Applications include quality assessment in food production, inspection of food quality by odor, control of food cooking processes, inspection of fish and monitoring of fermentation processes. Flavor is generally the most important sensory characteristic associated with foods. Flavor perception consists of two components i.e., taste and aroma. Taste arises from the perception of nonvolatile compounds whereas aroma is a result of the many hundreds of volatile compounds associated with food.
Researchers have investigated the response of an array of twelve tin oxide sensors to headspace of coffee packs. In that study, discriminate and classification function analyses were performed on the sensor array response to three commercial coffees as well as one coffee subjected to a range of six roasting times. The feasibility of using an electronic nose to classify coffee aromas was demonstrated with greater than 80% accuracy (see, Gardner et al., Sensor and Actuators B, 6, 71-75 (1992)).
In addition, a multisensor system was developed to discriminate between the aromas of different beers. In that study, 24 conducting polymer sensors were constructed to respond differently to the headspaces of beers and lagers. The output from the polymer array was preprocessed using a variety of algorithms and then classified using statistics (see, Gardner et al., Sensor and Actuators B, 18-19, 240-243 (1994)).
Moreover, U.S. Pat. No. 5,675,070, which issued to Gelperin, discloses an artificial olfactory system and associated method for identifying an object by its aroma. The artificial olfactory system includes a testing chamber in which are disposed an array of gas sensors. The object to be identified is placed in close proximity to the testing chamber. The air pressure within the testing chamber is then lowered below ambient, thereby causing ambient air to flow past the object being identified and into the testing chamber. As air flows past the object being identified, the aroma of the object becomes mixed with the air and is carried into the testing chamber. Once within the testing chamber, the air/aroma mixture is exposed to the array of gas sensors. The gas sensors detect the levels of various gases comprising the air/aroma mixture and produce a sensor pattern that represents the various gas concentrations detected.
Despite the advances made in the prior art, none of the aforementioned systems are designed for process monitoring xe2x80x9con-linexe2x80x9d or xe2x80x9con-the-fly.xe2x80x9d The prior art methods are performed xe2x80x9coff-linexe2x80x9d which is inefficient and takes more time. Thus, there exists a need for an electronic nose that is suitable for applications in food that allows for on-line analyses. The present invention fulfills these and other needs.
In certain aspects, the present invention provides xe2x80x9cin-linexe2x80x9d or xe2x80x9con-linexe2x80x9d monitoring of agricultural product qualities and agricultural product processes. As such, the present invention provides a method for monitoring a quality of an agricultural product on-line, comprising: training an array of sensors with a fluid associated with a known agricultural product to generate an acceptance level; contacting the array of sensors with the fluid or vapor associated with an unknown agricultural product to generate a response level; and comparing the response level with the acceptance level thereby monitoring the quality of the agricultural product on-line. As used herein, the term xe2x80x9cfluidxe2x80x9d refers to a solid, a liquid, a gas or a vapor.
In certain aspects, the agricultural product or process is exposed to a first sensor array to generate a first response. After the process is complete, or after a reactant is added, the product is contacted with a second sensor array to generate a second response. Preferably, the first sensor array and the second sensor array use similar, or the same sensing elements in each of the arrays. In this aspect, a comparison is made between a sample before it undergoes a process, such as a blending process, and then after the blending process is complete. By subtracting the second response from the first response, a difference pattern is obtained and thus, it is possible to ascertain the completeness of the process. Suitable processes include, but are not limited to, formulating, blending, mixing, reacting, pilot plant processing, determining the presence of microorganisms, etc.
In another embodiment, the present invention provides a method for differentiating between a quality of an agricultural product comprising: contacting a fluid associated with a first agricultural product with a sensor array to generate a first response; ii) contacting a fluid associated with a second agricultural product with the sensor array to generate a second response; and iii) comparing the first response with the second response, thereby differentiating between a quality of the agricultural product. In certain preferred aspects, the method is used to differentiate between product from various geographical origins, such as grapes from various regions.
In certain other embodiments, the present invention provides a quality control monitoring device, wherein the device comprises: i) a first sensor array at a first location to generate a first response; ii) a second sensor array at a second location to generate a second response; and iii) an analyzer to compare the first response with the second response.
In still yet another embodiment, the present invention provides a method for monitoring a quality of an agricultural product, comprising: (i) training an array of sensors with a fluid associated with a known agricultural product to generate a first residual standard deviation (s(e)2); (ii) contacting the array of sensors with the fluid associated with an unknown agricultural product to generate a second residual standard deviation (s(em)2); (iii) calculating a ratio between the second residual standard deviation and the first residual standard deviation (s(em)2/s(e)2); and (iv) comparing the ratio with an acceptability quotient (F1,df,xcex1) thereby monitoring the quality of the agricultural product. In certain preferred embodiments, the acceptability quotient is user selected. This selection can then be changed during the duration of an in-line process.
Using the devices and methods of the present invention, it possible to monitor various processes, such as agricultural processes, including for example, product formulating, product blending, determining the presence of pathogenic microorganisms, and the like.
Various qualities of agricultural products are suitably monitored using the methods and devices of the present invention. These qualities include, but are not limited to, fruit ripening, product blending, product formulation, product mixing, determining rancidity, determining authenticity and cooking processing.
These and other aspects of the present invention will become more readily apparent when read with the accompanying figures and detailed description which follow.